[RussianCow]

On macOS, Option+Shift+- and Option+- insert an em dash (—) and en dash (–), respectively. On Linux, you can hit the Compose Key and type --- (three hyphens) to get an em dash, or --. (hyphen hyphen period) for an en dash. Windows has some dumb incantation that you'll never remember.

[oblio]

For Windows it's just easier to make a custom keyboard layout and go to town with that: https://www.microsoft.com/en-us/download/details.aspx?id=102...

[withinboredom]

I prefer the linux compose-key style: https://github.com/samhocevar/wincompose

[Brian-Puccio]

On MacOS and iOS, two dashes (i.e., the -- characters) automagically turns into an em dash (—). No special commands needed.

[BizarroLand]

Alt+0151 or WIN+SHIFT+-, but I can't seem to make the WIN+SHIFT+- combo work in browser, only in a text editor.